“So that everyone across the board, hospitals, policy makers, insurance companies, can have tangible objective data … to talk about this type of thing," Ranzoni said, "about prices and reimbursement and what is right and what is fair.”

For common outpatient procedures, heart electrophysiology studies had the highest average cost: $37,000. For inpatient procedures, the highest average cost was for a heart valve replacement surgery: $85,000.

The procedure that saw the highest price increase in 2015 was a coronary bypass surgery. It rose by $8,700. Inpatient care accounts for as much as 30 percent of health care spending in Oregon, according to the latest figures.

Hospitals negotiate their prices with insurance providers, but prices can also depend on a number of factors like location.

Hospitals located where there’s a higher cost of living tend to pay higher salaries, leases and utility costs.

But that doesn't mean hospitals in larger cities always charge more, according to the report. Sometimes they can charge less for a procedure because they can make up the cost difference in volume.